Pneumatic horn



Jan- 15, 1934 E. E. HEWITT |=:r AL

PNEUMATIC HORN Filed July 25, 1952 .ngfsefff Patented Jan. V16, 1934 Lana/1 Partnr orrlcr.

PNEUMATIC HORN Ellis E. Hewitt, Edgewood, Pa., and Carlton D. Stewart, Berkeley, Calif., assigncrs to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application July 23, 1932. Serial No. 624,285

19 Claims.

This invention relates to pneumatic horns and more particularly to a sound producing device in which the vibration of a diphragm is produced by creating a partial vacuum on one side of the diaphragm and in which a valve is operated by the diaphragm to connect the partial vacuum side ci the diaphragm to the atmosphere.

An object of the invention is to provide a Y pneumatic signal horn of the above type in which certain new and useful improvements in construction and arrangement of parts combine to produce a compact device which may be manufactured at a comparatively low cost.

Another object of the invention is to provide l a pneumatic signal horn having the above noted characteristics in which the tone adjustment means is operable from the exterior ofthe horn. Y

Another' object of the invention is to provide -a pneumatic signalv horn wherein the diaphragm and valve are readily accessible for repair or replacement without necessitating complete dismantling of the device. y

A further object Yof the invention is to provide a sound producing device of the above type in which means are provided for limiting the vibratory movement of the disc valve so as to avoid undue strain on the valve. Y

Other objects and advantages will appear in the following more detailed description of the invention.

In the accompanying drawing; Fig. l is a sectional view of the sound producing device embodying our invention, associated with the intake manifold of an internal combustion engine and a storage reservoir; Fig. 2 is a view, partly in section, of the disc valve and stem assembly; and Fig. 3 is an enlarged sectional view showing the normal relationship between the valve for controlling the operation of the horn and the electro-.magnet for controlling the operation of the valve.

As shown in the drawing, the signal hornvmay comprise a casing l having a pair of chambers 2 and 3, each having a reduced bore 5,-in the Y outer end of which is secured one end ofthe sections of tubing 6 which are adapted to receive and retain one end of the usual sound amplifying horn tubes 7 for the purpose of reinforcing said horn, the horn tubes 'Tbeing preferably of unequal lengths so as to produce tones of different pitches.

Each of the chambers have an annular shoulder 8 to provide a seat for a peripheral flange 9 of the sound producing mechanism, which will now be described. y

The sound producing mechanism comprises an open ended member 10 in which the end openings are concentrically disposed and having at one end an annular valve seat l1 and at the other end the peripheral flange 9. Adjacent the outer face of the flange 9 is a exible diaphragm 12 of substantially the same diameter as the'v outer edge of the ange 9.

The diaphragm 12 is provided with an adjusting mechanism, for a purpose which will be hereinafter described, which comprises a member 13` rigidly secured or clamped to the diaphragm, centrally disposed thereof. In the present embodiment of the invention, said member has at one end a head portion which engages one side of the diaphragm and a shank portion 14 which extends through a central opening in the diaphragm and a registering opening in a washer 15 in engagement with the other side of the diaphragm, the outer end of the shank portion being peened over the washer to securely clamp the member 13 to the diaphragm.

The adjusting mechanism also comprises an adjusting member or stem 16 which has screwthreaded connection with the member 13 within a central bore 17v in said member, the outer end of the stem being provided with a slot 18 for the reception of a suitable tool for turning said stem. Alock nut 19 is provided for the purpose of locking the stem 16 in position. 35

Integral with the stem 16 and extending forwardly of the diaphragm is a body or stem portion 20 which may be larger in diameter than the stem 16 and which may have a peripheral flange 21. The outer face of the flange is cut away, as indicated at 22, Fig. 2, so as to provide a central iat surface 23 of less diameter than the diameter of the flange.

Clamped to the stem 20 in engagement with the aforementioned face 23 is a thin metal disc valve 24. According to the construction, a shank portion 25 projects from the face 23 of the stem 20, centrally thereof, and extends through a central opening in the disc valve 24 and a registering hole in a washer 26, the end of said shank being riveted over said washer.

The face of the Washer 26 adjacent to the disc Valve 24 is cut away, as indicated at 27, Fig. 2, so as to provide a central flat face 28 of less diameter than the diameter of the washer and of substantially the same diameter as the central flat face 23 on the stem 20.

It should be understood that the disc valve can readily flex in either direction from its normal flat or straight position during the operation of the device due to the fact that surfaces 23 and 28, between which the disc valve is clamped, are relatively small in diameter.

Pronounced steps 29 and 30 are formed between the portions 22 and 23 of the stem 20 and between the portions 27 and 23, respectively, oi this washer 26, and the peripheral edge of the iiange'ZI and of the washer 26 form the corners 31 and 32, respectively, the purpose of which will be hereinafter more fully explained.

It should here be noted. that 'the combined weight of the parts comprising the diaphragm and Valve assembly, including the diaphragm l2, the member 13, the stem i6, the washer 15,'

the lock nut 19, the stem 20 with its iiange 21 and shank 25, the washer 26, and the disc valve 24, operates to control the period of vibration of the diaphragm and is an important factor in the operation of the horn. In order that the combined weight of the parts may be of the precise amount, the form of the stem 20 may vary, in actual construction, from that shown in the drawing. Furthermore, in a multi-tone horn, such as is shown in Fig. l, the stems 2O may be dissimilar in size and form so that the combined weights of the respective associated parts will be different, which will cause the period of vibration of one diaphragm to be different from the period of vibration of the other diaphragm, with a resultant difference in the tones sounded by the horns.

The disc valve 24 is adapted to engage the aforementioned seat l1 provided at one end of the member l0.

The flange 9 of the member 10 and the peripheral edge of the diaphragm l2 are clamped between the shoulder 3 in the casing 1 and a rib 33 on a cover plate 34, with the valve seat 1l on the member l! disposed in the chamber 5, said cover being secured to the casing in any desired manner. A suitable gasket 35 is in-y serted between the shoulder 8 and the flange 9 of the member l0.

It will be understood from the foregoing that the sound producing mechanism may be readily removed for repair or replacement since the mechanism is assembled as a unit before being assembled in the horn and that said unit is accessible for removal merely by dismounting the cover plate.

To seal the chambers 2 and 3 from the respective chambers 5, an annular gasket 35 is pro vided between the wall of the member 10 and the casing l.

A chamber 37 is formed in the bore of leach member 1G by the closing off of one end by the diaphragm 12, said chamber being connected to the respective Chamb-rs 2 and 3 by means of an opening 38 in the wall of said member.

Within the confines of each rib 33 in the cover plate 34 is a depressed portion to provide a shallow chamber 3i) adjacent to each diaphragm 12.

To provide easy access to the adjusting mechanism, a hole is provided in the cover plate central with each s id adjusting mechanism, said hole being adapted to be closed by a plug 40, preferably of soft rubber, which may be snapped into position and which is, of course, readily removable. A port 41 is provided in each plug, so that the chambers 39 at the outer face of the diaphragms 12 remain at atmospheric pressure at all times.

For controlling the operation of the horn,- -a valve 42 is provided, the operation of whichis yneziaevi controlled by an electro-magnet which com prises a casing 43 having screw-threaded connection with the casing 1 within the bore 44 which may be disposed on the forward face of the casing 1 and between the horn tubes 7. The electro-magnet also comprises a winding 45, a spool 46 and a core 47, the end of the core being spaced from a lug 48 on the outer face of the valve 42.

The lug 48 and an adjacent portion of the outer face of the valve 42 is provided with a non-magnetic cover 52, as shown in enlarged section in Fig. 3,101' the purpose of preventing any residual magnetism from unintentionally maintaining the valve in open position. In the present embodiment of the invention, this cover is in the form of a thin brass plate which is adapted tov rit over the lug 48 and which is secured to the lug by bending over and then under an enlarged portion 49 of the lug.

The valve 42 is normally held seated on a seat 50 provided in the casing 1 by a spring 51 interposed between the valve and the spool 46, thereby closing olf communication between the passages 63 and 52 leading to the chambers 2 and 3, respectively, and a passage 53 which is connected to a source of vacuum.

As shown in Fig. l, the passage 53 may be connected to the intake manifold 54 of an irrternal combustion engine through a pipe 55 and to a storage reservoir 56 through a pipe 57, the latter connection being provided so as toensure a vacuum source at all times, regardless of whether or not the engine is running.

A check valve 58 is interposed in the pipe 55,

which is adapted to permit flow in the direction of the arrow, but prevents flow in the opposite direction, so that the vacuum accumulated in the reservoir 56 will not be lost by the `flow of uid from the intake manifold to the reservoir.

Of the two circuit wi1es759 for the magnet, one may lead to the usual push-button (not shown), for operating the horn and the other may lead either to said push-button or to the ground, depending upon the type of circuit employed on the Vehicle.

For the purpose of protecting the electro-magnet against the entrance of moisture, a cover 60, preferably of soft rubber, is provided, which` is adapted to t over the end of the casing 4,3 and is provided with an opening 6l for the reception of the circuit wires. Y

In operation, the electro-magnet is normally deenergized, so that the valve 42 will be held against its seat 50 by the spring 51. The chambers 37 and the chambers 39 atY opposite sides of the diaphragms l2 are then at atmospheric pressure, and the valve 24 may just touch the seat 11 or may even be slightly away from the seat.

A partial vacuum is created in the reservoir 56 by the running of the internal combustion engine, which creates a partial vacuum in the intake manifold in the usual manner.

When it is desired to operate the horn, the electro-magnet is energized in the usual manner and the magnetic pull of the magnet will unseat the Valve 42 against the light pressure of the spring 51 and the partial vacuum in the passage 53, thereby opening communication between the passage 53 leading to the source of vacuum and the passages 63and 52 leading to the chambers 2 and 3. Inasmuch as the chambers 2 and 3 are connected throughwthe openings `38-to the respectiv'chambers 37, a, partial'vacuum is created -in the chambers 37, causing the thin flexible disc valves '24 to'tightly' engage the seats 11, by the'actionoi` the at mospheric pressure which acts-on the' outer facer of 'the Avalves and even "if 'the disc 'valves bev slightly away from the'seats,v thediscs -Willfbe exed so as to tightly `engage vthej's'eatsl 'The atmospheric pressure l"in lchambers 39y moves the diaphragms 12Y toward'the'fleft hand against the Yreduced pressure in the chambers 37 and with' them the valve A'stems 20. -The disc'valves 24, being of thin' flexiblemateriaLf tend to hold to their seats and flex during the slight initial movement of the stem720 toward the left hand; dueto the atmospheric pressure acting on the outer face ofthe valves vagainst the partial vacuumin chambers B'Yf'andA then the valves are forcibly pushed from their? seats so that a relatively large opening is created from chambers -37 to chambers `5 and the interior of" the horn tubes y7. Av sudden flovvof vairv then takes place from thev chambers 5 andtheliorn tubes 7 to the chambers 3'1, causing thequick` build up of pressure inchambers 37, [so that the diaphragms .12,4Which are now flexed out of ytheir*` normal positions, move back to their'orig'inal positions, aided by the springfactio'nfof' the Adiaphragms The disc valves 24 again seatfon the seats ll, so as to cut offthe inflow of air to the chambers 3'7l and then apartial vacuum is again created in chambers 37, so that the diaphragms 12 again'm'ov'e tovvardthe left hand,

The diaphra'gms 12 are thus caused' to vibrate, and by the opening andv closing Aof the valves 24, the air column in the horn Vtubes v'7v is caused to pulsate and thus 'produce a sound. Because ofthe difference in the period: of'vibration of the two diaphragms clue to' the'difference in Weight of theV diaphragm and valveas'sembly, as hereinbefore mentioned, andthe difference in the length of the horn tubesfsounds o'fndiffer-- ent tones areY produced. By reason of the aforementioned adjustment means', the sound produc-Y ing mechanism may be adjusted to produce harmonious tones pleasing to the ear. a

yIt Will be understood that, by reasonf ofthe adjustment means, the sound producing mecha'- nism may be caused to operate satisfactorily, vre-` gardless of variations vin manufacture and "re` gardles's of physical changes Which lthe sounding mechanism may undergo vin service, which Would affect theY position of the valvefrelativefto` its seat.

the degree of fiexure of the disc valve 24 sothat the valve Will not be subject to undue strain. This4 is accomplished by providingthe 'aforementioned peripheral edge 31 on thegange 21 on the stem 20'and the peripheral edge; 32 `on the lWasher 26. NWhen the disc 'valve is flexed in the'one direction, it will engage the ed'gef31, andwhen it is flexed in theother c lirection it Will engage the edge 32. The degree of exure is thus limited to a small amount so that thclas-A tic limit of the disc valve will notbey reached..

It is vapparent from the foregoing that the construction of the hornisV simple, that the sound"producingfmechanism may be readily assembled in and removed from the'horn and that the adjusting mechanism is `easily yaccessible from the exterior of the h'orn casing. -It Vis also apparent that the disc valve will'remain in operative condition over a long period of time due t is desirable to provide means" for limiting tothe means provded'for protecting said valve against undue straim 1 While one illustrative embodimentl of the invention has been described in detail, it is not ourintention-'to limit its scope to that embodimentor `otherwise than by the terms of the ape pended'claims. f V

favin'gnowdescribed ourfinvention, what we claim as fn'ew'land -desire to secure by Letters Patent, is: f

' 'lj; A sound producing device comprising a cas# lng, a vflexible diaphragm mounted in said lcasing, a thin disc'valve'operated by said diaphragm, a stem secured to said diaphragm and carrying atits` outer end said valve, the portion of saidl stem Iengaging said valve having-a surface of relatively small *area anda: surface of greater area spacedslightly Ifrom* said valve Whensaid valve is'in'ts normal position, a Washer disposed on the Vside of said valve opposite to said surfaces on the stem, said washer having a surface of relatively small areav engaging said valve and a surface of Agreaterfarea spaced slightly from said valve when said valve is in its normal position, and means for rigidly securing said washer and said valve to said stem, comprising a headed shank projecting forwardly from the stem and passing through an openingin the valve andan opening in the Washer.

2.' A sound producing device comprising a cas ing, a flexible diaphragm'mounted in said casing, a thin" disc valve operated -by saidl diaphragm, a stem secured to said diaphragm and carrying at its outer end said valve, the portion of said stem engaging said valve having a surface of relatively small area and a surface of greater area spaced slightly from said'valve when saidvalve is in its normal position, a Washer disposed on the side of said valve opposite to said surfaces on the'stem; 'said Washer having a surface of relatively small area engaging said valve and asurface of greater area spaced slightly from'said valve Vwhen said valve is in its normaliposition, and means for rigidly securing said washer and said valveto said stem.

3.v A sound producing device vcorrlprising a casing, a flexible diaphragm mounted rin saidcasing, a thin disc valve operated hy said diaphragm for varying the uidpressure on said' diaphragm,

a stem carriedby said diaphragm to which the Quo varying the fluid pressure on said diaphragm, a

stem'ciarriedfl by" said diaphragm to which the valve is screwed, and annular flanges'fcarried by saidstem'and spaced from said valve for Aengaging saidvalve upon a predetermined ilexingv of thervalve in eitherrdirection.

5.y A sound producing device operable by fluid pressure, comprising a thin flexible disc valve, a stem `to which said valve is screwed, and means f for modifying theV flexing of said valve, compris" ing members carried by said stem and spaced from said valve for engaging said valve upon a predetermined flexing movement of the valve.

Y 6. Afsound producing device operable by fluid pressure, comprising va diaphragm, a stem -se cured to said diaphragm, a'valve seat, a valve mounted on the other end of saidstem and mov-'I able'into and out of engagement with said seatg. bysaid diaphragm, and means cooperating with said diaphragm and stem and adapted to be operated for varying the effective length of said stem to adjust the position of said valve relative to said seat.

7. A sound producing device operablev by fluid pressure, comprising a diaphragm, a stem secured to said diaphragm, a valve seat, a valve mounted on the other end of said stem and movable into and out of engagement with said seat by said diaphragm, and adjustment means cooperating with said diaphragm and stem and operable for adjusting the effective length of said stem to thereby vary the position of said valve relative to said seat.

8. A sound producing device comprising a casing having a chamber, a cover having aI chamber, a exible diaphragm clamped between said casing and said cover and forming a partition wall between said chambers, a valve seat, a stem carried by said diaphragm, a valve mounted on the louter end of said stem and adapted to seat on said valve seat, and adjustment means carried by said diaphragm for varying the position of said Valve relative to said sea't, said cover having an opening through which said means may be adjusted.

9. A sound producing device comprising a casing having a chamber, an open-ended member extending into said chamber and having -at one end a valve seat, a chamber in said member, a exible diaphragm subject to variations in fluid pressure in the second mentioned chamber, a stem secured to saiddiaphragm, and a valve mounted on the outer end of said stem and adapted to seat on said valve seat.

10. A sound producing device comprising a casing having a chamber, an open-ended member extending into said chamber and having at one end a valve seat, a chamber in said member, a exible diaphragm subject to variations in fluid pressure in the second mentioned chamber, a member secured to said diaphragm and having an opening, screw-threads on said member within said opening, a valve adapted to seat on said seat, a stem carrying said Valve at one end, the other end of said stem having screwthreaded engagement with the second mentioned member and passing through and projecting beyond said diaphragm, said stem be1ng rotatable to adjust said valve, and means on said stem for facilitating the turning of said stem.

11. A sound producing device comprising a casing having a chamber, an open-ended member extending into said chamber and having at one end a valve seat, a chamber in said member, a flexible diaphragm subject tor variations in fluid pressure in the second mentioned chamber, a member secured to said diaphragm and having an opening, screw-threads on said member within said opening, a valve adapted to seat on said seat, a stem carrying said valve at one end, the other end of said stem having screwthreaded engagement with the second mentioned member and passing through and projecting beyond the second mentioned member, said stem being rotatable to adjust said valve, andmeans on said stem for facilitating the turning of said' stem.

12. A sound producing device comprising a casing having a chamber, an open-ended member extending into said chamber andhaving at one end a valve seat, a chamber in said member, a llexible diaphragm subject to variations in fluid pressure in, the second mentioned chambei', a member secured to said diaphragm and having an opening, screw-threads on said member Withinsaid opening, a valve adapted to seat on, said seat, a stem carrying said valve at one end, the other end of said stem having screwthreaded engagement with the second mentioned member and passing through and projecting beyond said diaphragm, said stem being rotatable to adjust said valve, means on said stem for facilitating the turning of said stem, and. means for locking said stem in adjusted positiion.

13. A sound producing device comprising a casing having a chamber, an open-ended member extending into said chamber and' having at onev end a valve seat, a chamber in said4 member, a exible diaphragmv subject to varia-- tions in fluid pressure in the second mentioned chamber, a member secured to said diaphragm and having an opening, screw-threads on said member within said opening, a valve adapted to seat on said seat, astem carrying said valve at one end, the other end of said stemV having screw-threaded engagement with the second mentioned member and passing through and projecting beyond the second mentioned member, said stem being rotatable to adjust said valve, means on said stem by which said stem may be turned, and means for lockingv said stem in adjusted position.

14. A sound producing device comprising a casing, a flexible diaphragm mounted in said casing, a member mounted on one side of said diaphragm and having an opening, screw-threads on said member within said opening, means forY rigidly securing said member to said. diaphragm comprising a washer disposed on the side of the diaphragm opposite to said member and a headed shank projecting rearwardly from said member and passing throughV the diaphragm and washer, a stem, a valve seat, and a valve carried at one end of said stem and adapted to seat on` said valve seat, the other end of said stem having screw-threaded engagement with said member and having means for facilitating the turning of said stem for` varying the position of said.

valve relative to saidseat. Y

15. A sound producing device comprising a,

casing having a chamber, a cover'having a chamber, a flexible. diaphragm clamped between said casing and saidy cover and forming. a partition wall between said-chambers, a valve seat, a stem carried by said diaphragm, a valve mounted on the outerend of said stem and, adapted to seat on said valve seat, adjustment means carried by said diaphragm for varying the position. of.

said valve relative to said seat, said coverY having an opening4 in alignment with saidv adjustment means, and aremovable plug in said opening..

16.` A sound producing device comprising a casing having a chamber, a coverhaving a chamber, a flexible diaphragm clamped between said casing and said cover and, forming a partition wallbetween said chambers, a valve seat, a stem carried-by said diaphragm, a valve mounted on the outer end of said stem and adapted to seat on saidvalve seat, adjustment means carried by said diaphragm for varyingthe position of said,

valve relative to said seat, said cover havingan opening inV alignment with said adjustment means, and a removable plug in. said opening,

in said chamber through one of the open ends comprising a hollow member, a valve seat on said member, a valve adapted to engage said seat, a cover for clamping said hollow member to said casing, and an annular gasket in sealing engagement with said member and casing.

18. In a sound producing device, the combination with a casing, of a sound producing mechanism in said casing, said mechanism comprising a stationary element and afflexihle diaphragm dening a chamber adapted to be connected to a source of partial vacuum, a Valve seat on said element, a valve operable by said diaphragm into and out of engagement with said seat for controlling a communication from the atmosphere to said chamber, acover secured to said casing clamping said mechanism to said casing, and a gasket cooperating with said element and casing for preventing the leakage of fluid from the atmosphere to said chamber and source of Vacuum exteriorly of said element.

19. In a sound producing device, the combination with a casing, of a sound producing mechanism mounted in said casing and comprising a diaphragm having a chamber at one side constantly open to the atmosphere and having a chamber at the other side adapted to be placed in communication with the atmosphere and adapted to be placed in communication with a source of partial vacuum, a valve seat member separate from said diaphragm, a valve operable by said diaphragm into and out of engagement with said valve seat member for controlling the communication between the atmosphere and the second mentioned chamber when the second mentioned chamber is connected to the source of partial vacuum for controlling the operation of said diaphragm, and electrically controlled means for controlling the communication from said partial vacuum source to the second mentioned chamber.

ELLIS E. HEWITT. CARLTON D. STEWART. 

